Let's Build a Model Steam Engine - Machining a Piston!

This episode on Blondihacks, I'm making the piston and related stainless bobs for my steam engine! Exclusive videos, drawings, models & plans available on Patreon!

Here are links for many of the tools that you see me using:
(I earn small commissions on these links)

Want more content like this? Try these places:

As an Amazon Associate, I earn from qualifying purchases.

[broheim]

I've gotta hand it to you, Quinn: since deflection was such a problem, cutting half the threads by single-pointing and then finishing with a die was an excellent idea! I'm going to remember that one.

[firebird]

Blondihacks time! So glad I procrastinated changing my brakes on the truck.

[Blondihacks]

Hey everyone! Something I forgot to mention in the video that’s important for hobbyists: Make the cylinder first, because it’s a lot easier to hit a precise dimension on an OD than an ID, especially on hobby equipment. It’s much easier to let the cylinder be whatever it turns out, then fit the piston to it, than the other way around. You can always emery-paper your way down with an OD when you need to nail a dimension.

A lot of people are also mentioning the piston mounting. To be clear- the piston is not supposed to be threaded in this design. I did not change that. I only added a smooth shoulder to the rod. You can argue about whether an unthreaded piston is a good idea, but that is the design from the company. 🤷‍♀️

[carlwilson]

That was very good. I was pleased to see you promote Mr. Crispin. He is Rolls-Royce's finest. To see him part off using a drill is to see poetry in motion.

[MrCulldog]

Down at the steam shop we have the pistons out of our locomotive for a rebuild (a 1924 4-6-2 passenger locomotive built by Alco). The main cylinder is 30” in diameter and the pistons look exactly like yours. The key difference being that these are double expansion steam engines. This is Great work! Loving this series!

[TheKnacklersWorkshop]

Hello Quinn,
An enjoyable video and a good outcome.. I am off to refresh my memory on nut making with Mr. Crispin. He is a very knowledgeable engineer and I am sure will be grateful for your shout out...
Take care
Paul, ,

[retromechanicalengineer]

Great job. Glad you mentioned Mr Crispin, he's a bit of a legend over here in the UK. As I was watching your video I thought that you needed his special parting tool and then you mentioned him. Dean in Oxfordshire UK.

[oldhick]

You people and your precise measurements, fine surface finishes and your flat, plumb and level Nice work !

[g.tucker]

Nice tip about the hybrid threading methods. Wish I had known about that sooner… :)

[elsdp-]

THANK YOU...for sharing. One beautiful job on the rod and piston. Very nice.

[Pauly]

I really enjoyed watching that. Thanks for making and sharing it. I felt satisfied when the piston fitted so nicely.

[gagasmancave]

Another step closer to steamy operation. Great instructive bid Quinn
Regards Nigel

[jerseyjoe]

You can measure the groove depths (minor diameter) for the rings by miking over gage pins or small drill bits that fit in the grooves.
Then subtract the combined thickness of the two pins to get the inside diameter.
Divide by two to get the depth.

[pudster]

Quinn, the way you do your videos is top notch. Vey enjoyable to watch, you can tell that you put a lot of time into them. I love your way of showing how to do things too. You are a great teacher of your way of doing things. I love it!

[TheMechanic]

I don’t know why but this is the part I’ve been looking forward to the most.

[pointerg]

I really like your can-do approach to things. I just found your channel and am enjoying the work you do.

[ironhorse]

Very nice job Quinn. I like the technique of chamfering on the chuck side when needed with a swiss file. Thank you. Really good job !

[captiveimage]

Looks beautiful. Can't wait to see this running 😍

[splinky]

You should try some 303 for small machined part in stainless....there’s a big difference between it and 304....in rod form it’s not much more expensive

[byronnelson]

My new steamer has a built up piston like you show. Stretching Teflon o rings over a traditional piston does by work very well. I used this uiltnup method for boiler to o rings on my new electric. boiler.